Commentary & Analysis
Drupa 2012, the Inkjet Drupa…again? A closer look at Xerox
In this fourth article of the series, David looks at Xerox, its production inkjet offering and application.
By David Zwang
Published: November 28, 2011
While Xerox has been around since 1906, its real rise to fame occurred with the introduction of the Xerox 914 in 1959. It was the first plain paper photocopier based on electro-photographic imaging (EPI). Its prominence in the photocopier space has led to its name, Xerox, becoming a generic way to describe a photocopier from any manufacturer. It is a company which prides itself on research, and in 1970 Xerox opened Xerox PARC (Palo Alto Research Center) where many inventions that have become an integral part of our lives were developed. Many of the stories and inventions have been recently been discussed with the passing of Steve Jobs of Apple. However, the laser printer, which Xerox invented in 1969, was the product technology that transitioned Xerox from a copier company to a printer company.
Xerox has been involved in inkjet for more than 20 years. For the first 9 years, the focus was on creating and selling products using aqueous-based inkjet using Piezo drop on demand heads. In 2000, Xerox acquired Tektronix, an Oregon company that had developed a printer based on a waterless phase change technology that would melt solid ink and then apply it to media. After the acquisition, Xerox continued to develop this product line and associated technologies, sold as its Phaser line of products. This development work ultimately led to the development of its new production inkjet product.
A primer on Xerox CiPress Production Inkjet technology
On the surface it would seem that Xerox is just another company using Piezo drop in demand inkjet technology, although this would be a major mischaracterization. First and foremost, its inkjet technology is not water based. More on that later.
Xerox uses its own specially designed Piezo printheads. Each printhead has 880 nozzles that are capable of firing 39,000 times per second. It has its own on-board memory, ink reservoir and temperature controls. There are 14 printheads per color (CMYK) for a total of 56 printheads totaling 49,280 individual jets. Each jet is tunable to control dot size, and has a firing waveform that characterizes it to ensure reliable output. This is stored on the printhead on-board memory. Xerox also uses Stochastic screening and drop placement to optimize the ink usage and image quality. The heads feed real time performance data, including age and amount of ink that has been through it, back to the system controller where the information is used to optimize the firing voltage of each jet. Additionally, an intelligent sensor scans the printed sheets and collects image information by looking at patterned images printed on the web by the printheads. This image information is used to determine and adjust the position of the printheads across the web; it is also used to determine if there are any missing jets. Additionally, the image information is used to measure the position of each drop in the web direction (along the web). If, for example, a nozzle of a printhead is firing a little slower than the other nozzles in that same printhead, causing it to be misplaced in the image, the sensor sees this and the system corrects for this by firing that jet a little earlier than the others. If the sensor sees a missing jet, it will alert the system which will then instruct neighboring jets in the printhead to put down more ink to fill in the streak caused by the non-firing jet. There is actually a color-coded software system that visually shows the operator the condition of each head. It identifies whether a head requires maintenance or is in failure mode. While heads seem to have a long life, in case of failure, printheads can be replaced quickly by the user. They are refurbished upon return to Xerox. Printhead maintenance is an important operator responsibility, as it is with all of the production inkjet machines. To make this more efficient, CiPress head cleaning is a fully automated process that requires no manual intervention.
The Print Box Unit is mounted on the frame and includes the print bar assembly, to which the printheads are mounted. The heads are mounted in groups of either 3 or 4, and staggered across and around the imaging frame to ensure complete imaging, even with problem heads. The heads float on the print bar assembly, to allow for on-the-fly alignment at the pixel level to control color-to-color registration. The Print Box Unit also contains the head control electronics and the ink distribution system. Currently the press supports 4 colors (CMYK), but the frame can support 2 extra colors for addition at some point in the future. It also currently does not support MICR, but there is an expectation that this support may be announced at drupa.
A unique feature of the Xerox inkjet press is the fact that it uses waterless ink. In essence, the patented polymer ink has its “phase changed.” In other words, the solid granules are melted and then jetted onto the paper. But there is a lot more to it than that. If you recall from the previous articles on HP and Kodak, when using aqueous based ink you need to pre-treat the paper with a hydrophobic coating in order to keep the ink on the surface. It also requires drying the printed paper to remove the water. In the Xerox system, there is no pre treatment of the paper or show through due to absorption because the ink uniformly bonds to the paper fibers. It does this by heating both the ink (to melt it) and the paper to ensure a good bond once pressure is applied by the spreader drum.
This means you can use many of the same papers you currently have on hand and use for offset printing. Currently the only real downside is that the process doesn’t work with glossy coated papers, although that will probably be addressed in the future. There are other benefits to waterless ink, like reducing the risk of substrate curling or puckering from the water, although most of the other press manufacturers control that through various drying techniques. Another distinguishing feature of the Xerox waterless ink, is that there is a higher gloss, without any coating, than the water based inkjet solutions I have seen to date.
The non toxic, non-VOC (Volatile Organic Compounds), dry granule ink comes in 10kg containers that are used to fill permanent and refillable 35-gallon barrels for each color. The ink is fed into ink melters that melt the granules and feed it through heated supply tubes to the Print Box Unit, then to the printheads using automotive industry fuel injectors. Ink level sensing thermistors inside the printheads send a request to the injectors in order to keep the printhead reservoirs filled. The entire ink delivery system is sealed to outside air to protect it from any environmental changes.
The Press Transport
Each roll-fed print engine supports single-side printing, so duplex printing requires two engines. The press is rated at 500 ft/min at 600 x 400 dpi, with a color gamut comparable to offset printing on uncoated paper. It has a duty cycle of about 50 million single-side letter pages, or 11.5 million ft. per month on a twin engine duplex system. The system doesn’t require any external venting as a result of the non-VOC inks. Additionally, lack of dryers produces a lower power demand than what is usually required in an aqueous based ink system.
As you can see, a significant amount of new engineering went into developing a high-speed waterless system, including many process control systems I haven’t touched on, but the print process is rather straightforward. The web is fed into the machine, the web cleaner removes dust and chads, and the web is warmed with a low-temperature ceramic heater. The ink granules are melted to a liquid molten ink and jetted directly onto the web, where ink hardens instantly. After bonding, the web is then cooled.
The CiPress 500 supports plain paper that is uncoated. Including offset, recycled, newsprint, calendared, ground wood, mechanical fiber, bond, and laser. The minimum media weight is 50 gsm and the maximum is 160 gsm. It supports a minimum paper width of 9”, and a maximum of 20.5”. The printable area is 19.5”. It runs roll to roll, roll to fold, and roll to sheet, with support for many 3rd party pre and post finishing solutions.
Xerox Front End
Xerox uses its FreeFlow Print Server to drive the CiPress. As we have seen with the other systems, this press requires significant computing power to process the files and control the press. At the heart of the server is the Adobe PDF Print Engine (APPE). The CiPress accepts all of the necessary file formats, including VIPP, IPDS, PDF, and DSC compliant PS, and supports native JDF and JMF control and communication. It has a scalable architecture that starts with 1 Application server and 3 RIP servers per print engine, and can include up to 14 RIP servers with parallel RIP architecture supporting multiple RIPs (up to 84), 2 video servers, 12 data connections, 336 GB of RAM and 25 TB of job spooling storage.
Putting it to use
The phase change ink granules, printheads, and spreader oil are the only user replaceable consumables. Xerox offers different maintenance plans to ensure cost competitiveness. The TCO (Total cost of Ownership) is competitive with its competitors.
During a recent trip from Graph Expo in Chicago to the corn fields of Iowa, a group of analysts, including myself, had a wonderful opportunity to see the first CiPress installation. It was at dmh Marketing Partners, one of the largest direct mail companies servicing non profit markets. This company has a wide variety of printing equipment including offset, EPI and inkjet. The current installation is in a temporary space and is to be moved after internal testing is completed. That speaks to the lack of extensive installation requirements needed to support venting, etc. The machine had been running since January 2011.
Randy Seberg, CTO of dmh Marketing Partners, has been thrilled with the new press, and more importantly, the partnership he has developed with the Xerox development group. He has been hammering away at the press with real work, and not going easy on the press or Xerox. Xerox has been very responsive to him and the real-world experiences he is delivering. There were four very memorable observations he made during our visit. First, he found the press to be extremely consistent from the first sheet to the last. Next, he can just use paper he has in the warehouse without any pre-treating. Additionally, he found that the lack of water on the paper made it much easier to finish. Finally, his operators only needed minimal skills and training.
In the next article, I will continue the pre-drupa education by looking at the Oce production inkjet offerings and applications. In each subsequent article we will look at a different vendor’s offerings.